Bad NBSU Or A Gremlin

[thechevyhdman]

Ok, I went ahead and changed my NBSU well over a year ago to a "brown" one. Last tuesday I start up my truck and head out to my last lawn across town...rainy but not pouring. Typical shift selector indicator disappeared. But I also didnt have any fuel guage, water temp,rpm, or tranny temp guages...All I had was a SES and voltage and speedometer. Stuck in 3rd and man did it bang into gear like a nuetral drop. So I kept my old "black" NBSU went home slapped her in same shizit....Figure maybe I should pull the TCM fuse and see what that brings....I ended up pulling the fuse for inst. cluster(nothing) Pulled fuse for TCM (nothing) Turn the key off and start again...all is working fine.
My question is.. Say my TCM was getting no power at all, nothing. Would my truck even start? As maybe in pulling the fuse I "fixed" a loose wire. I know that the truck will run fine with no Instrument cluster so then that rules out that from being a problem.
What I am asking is was it my NBSU or something else...Either way now I got 2 free NBSU's. But no definite answer.
Bill

[Silver Bullet]

Check this out... HELP! battery in message center, haywire gauges, and limp mode!!! (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=3;t=005992)

My problem which I thought was the NBSU (again!) turned out to be a fuse connection in my fuse block.

[GMC-2002-Dmax]

Originally posted by thechevyhdman:
Ok, I went ahead and changed my NBSU well over a year ago to a "brown" one. Last tuesday I start up my truck and head out to my last lawn across town...rainy but not pouring. Typical shift selector indicator disappeared. But I also didnt have any fuel guage, water temp,rpm, or tranny temp guages...All I had was a SES and voltage and speedometer. Stuck in 3rd and man did it bang into gear like a nuetral drop. So I kept my old "black" NBSU went home slapped her in same shizit....Figure maybe I should pull the TCM fuse and see what that brings....I ended up pulling the fuse for inst. cluster(nothing) Pulled fuse for TCM (nothing) Turn the key off and start again...all is working fine.
My question is.. Say my TCM was getting no power at all, nothing. Would my truck even start? As maybe in pulling the fuse I "fixed" a loose wire. I know that the truck will run fine with no Instrument cluster so then that rules out that from being a problem.
What I am asking is was it my NBSU or something else...Either way now I got 2 free NBSU's. But no definite answer.
Bill William,

I know what it is, it's a Chevy tongue.gif , shoulda got a GMC :D .

Seriously, wish I could help ya, maybe Mac and I could stop by and see what's what.

GMC ;)

[thechevyhdman]

Silver Bullet, I spoke to you about this a while back, I could not duplicate the problem while lightly shaking the fuse block. I did check the wires etc like you did, And couldnt find a problem. My truck had the same brain fart as yours since april. (What did you do for a cure) But what doesnt make sense Is I would doubt the truck can even move/start If the TCM and tranny got no power at all...I dunno, Or if just the TCM wasnt getting power, then why no guages and vice versa

Hey Tony Bologney,I think shes fixed, but we will see. I always got a gas can and a Zippo lighter near by.....Of course all my add-ons will be magically missing at the time the truck roast starts....Yours might be next...Fox peccker red trucks have been known to instantaneously start on fire round here....Of course you could be my dumb arse and be in such a hurry to jump out and take a leak before hitting Tappan Zee traffic your passenger side door clobbers a mile marker post. D'OH If you heard the story of what occured before that(ask Mack) you can see I am the King Of Bad Luck :mad:

[Gbenzx01]

chevyhdman,
I did not run the search but it sounds a lot like the prob they have with the 4x4 switch that I think is at the aux gear box.
What a clicker! Hope you get er right...

Gben

[thechevyhdman]

O another big point I missed every time this has occured....been wet or damp out, Just this time It wasnt a one time fart that just went away as soon as it showed up. I would get the lights like SB would, and the tranny would burp,like it went into neutral...this time just flat out died....It aint easy pulling a trailer from a dead stop in 3rd gear either :eek:

[77TransAm]

thechevyhdman, I don't have much help for you on the root cause of your problem, but I can answer your question about the TCM. The truck will start and run fine with no TCM, but you will only have P,R,N, and 3rd, and it will SLAM into gear because the trim valves are not modulating the shifts.

[Silver Bullet]

Chevyhd,
My fix was to replace the fuse block in the cab by the DS door. The dealer told me that one of the fuses was not making a good connection (b/c I stretched out the connector in the block...D'OH!!!). I would lose most of my gauges and go into limp mode. The reason for limp mode was explained to me as when the fuse would lose contact, the TCM would not be able to communicate with the truck (ECM maybe)(or the truck couldn't communicate with the TCM) causing the limp mode. I have not had a problem since the fuse block was replaced.

[dmaxalliTech]

sounds like an ignition switch problem to me...

[Silver Bullet]

ignition switch is what my dealer originally thought and replaced it...but in my case that was not it...